Nitric Oxide Synthase oxygenase domain (NOSox) oxidizes arginine to synthesize the cellular signal and defensive cytotoxin nitric oxide (NO). Inhibitors of NOS are desirable both for medicinal purposes and to advance our understanding of basic physiology. We have recently solved the structure of inducible NOS (iNOS), and now have soaks and co-crystals with various inhibitors. The crystals are small and diffract to less than 5 E on a rotating anode. We propose to collect data on numerous iNOS inhibitors.